We show that all of the relevant features of a phase transition can be determined using a non order parameter field which is a physical state of the theory. This fact allows us to understand the deconfining transition of the pure Yang-Mills theory via the physical excitations rather than using the Polyakov loop.
@article{arxiv.hep-ph/0301229,
title = {Critical Behavior of Non Order-Parameter Fields},
author = {Agnes Mocsy and Francesco Sannino and Kimmo Tuominen},
journal= {arXiv preprint arXiv:hep-ph/0301229},
year = {2009}
}